With the bandolier function, you can swap instruments out. With the macro limit, you won't be able to do a lot each macro.
Any way, start by bring up the bandolier window (B key). Uncheck the automatically activate or whatever it is called. It's a checkbox and makes selecting a bandolier set automatically activate it. This makes it alot harder to setup new sets. If you like it that way, you can re-check it when done setting up your new sets.
Put what weapon and/or instruments you want in your primary and/or secondary slots, select the first set (should be unnamed at this point), click on the Add button and give it a name (example is Drums for a percussion instrument set). Repeat this process for all the sets you want or until you fill up all the sets.
Once you have the bandolier set up, you can make macros like the following:[pre]
/pause 3,/bandolier activate Drums
/pause 3,/cast 1
/pause 3,/cast 1
This will switch to the Drums bandolier setup, and try to cast spell gem #1 twice (general way to do bards, as fast recasts, will if a song is already playing, stop the song with the first cast, and start the new song with the second, but if no song is playing, the first will start the song, but the second cast is so soon it is ignored, because the song hasn't finished starting). I may be wrong on the double casting, it's been a few years since I played any of my bards to remember how the macros where set up exactly.
Hope this helps some,
Yther Ore.